https://doi.org/10.1140/epja/s10050-026-01891-8
Regular Article –Theoretical Physics
The 
-spectrum in rare earth nuclei within the pseudo-SU(3) shell model
1
Instituto de Ciencas Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior S/N, 04510, Mexico City, CDMX, Mexico
2
Frankfurt Institute for Advanced Studies, J.W. von Goethe University, Ruth-Moufang-Straße 1, 60438, Frankfurt am Main, Hesse, Germany
3
Maharishi Markandeshwar, Deemed to be University, 133-207, Mullana-Ambala, India
a
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Received:
27
April
2026
Accepted:
26
May
2026
Published online:
27
June
2026
Abstract
The study of the structure of the spectrum in heavy nuclei has drawn much attention in the last 2 decades. In this contribution we study their properties from a microscopic point of view. The pseudo-SU(3) model (
is applied to some rare earth nuclei, namely to Sm, Gd, Dy, Er, Yb and Hf isotopes. It is shown that the spectrum, and the accumulation of states at certain energies, can be well understood using this microscopic model, which takes into account the Pauli Exclusion Principle (PES). Intentionally, a very simple model Hamiltonian is applied and only the valence shell is taken into account, in order to high-lighten certain cross features. It is demonstrated that the microscopic Hilbert space is essential in understanding the accumulation of -states. A discussion to other models is provided. Also the dominance of B(E2)-transitions from the 
-band over those from the 
-band turns out to be trivial, in contrast to within some collective models.
Communicated by Mark Caprio.
Peter O. Hess and Sahila Chopra were contributed equally to this work.
© The Author(s) 2026
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